FI113326B - Controlling the image server - Google Patents

Description

1 113326

Controlling the image server

Field of the Invention

The invention relates to image servers, in particular to transmitting images on the basis of requests made from an image server to a user.

Background of the Invention

The image server is a device connected to a data network, typically a network server, to which one or more cameras are connected. The image server directs the cameras to take pictures according to user requests and sends the pictures in response to the user. The camera is arranged to take images of, for example, the surrounding area for monitoring purposes and the camera can be targeted to the target. Requests are transmitted by users to a server, typically through a communications network, which defines the image that the user would like to receive. Traditionally, monitoring servers controlled by image servers have been used to transmit, for example, video to a remote location. In such systems, it has been common practice for the system to comprise multiple cameras operated by a single user.

In recent years, as the Internet and other public information networks have become more widespread, there has been a need for image server systems where images taken by a single camera can be transmitted from an image server to multiple users. In such cases, a mechanism is needed to manage the control requests, so that control requests come from multiple users. The server controls the camera to: - take pictures according to the requests and pass the pictures to the user. The user may. · For example, request a single image either one at a time or periodically, or if. ·: Want to play a video image, multiple consecutive images.

Known image server solutions are described, for example, in JP 10164562, JP 2001157105, JP 10341429, US 6 133 941, EP 845 904, JP 2 001 008137 and US 5 521 631.

> * ·

A problem with prior art image server solutions is the situation where multiple users present multiple, substantially simultaneous; ·: 30 image requests to the image server. The image server handles image requests typically ... in first order. There is always some delay in taking an image as requested and passing it back to the user. In particular ν ·: Images transmitted over a wireless connection typically need to be encoded and compressed, which further causes additional delay. Thus, if the image server-35 receives multiple almost simultaneous image requests, this will inevitably result in a significant delay in image processing, at least for some image requests. This is a major disadvantage especially when the user wants to get near-real-time video from the camera they define.

BRIEF DESCRIPTION OF THE INVENTION The object of the invention is thus to provide a method and an apparatus implementing the method so that the above problems can be solved. The object of the invention is achieved by a method, an image server and a computer program characterized by what is stated in the independent claims.

Preferred embodiments of the invention are the subject of the dependent claims.

The invention is based on the fact that the image server comprises a buffer memory for storing image files taken according to predetermined parameters, preferably including a time stamp specifying the moment of capture. In this case, when an image request is sent from the user terminal to the image server, the predefined parameters and the parameter defining the maximum age allowed for the image file are appended to the image request. First, the predetermined parameters of the image request are compared with the corresponding parameters of the image files contained in the buffer memory, and if the buffer memory comprises an image file corresponding to the parameters specified in the image request, then the para:; meters in the timestamp of that image file. If this timestamp indicates that the k-wake moment is within the maximum allowable age, this image in the buffer memory is transmitted to the requesting user terminal.

According to a preferred embodiment of the invention, the image request is transmitted to the camera only if either of the above conditions is not met; . t if the image specified by the image request parameters is not found in the buffer memory or if the image specified by the image request parameters is found in the buffer memory; '30 but its timestamp indicates that the moment of capture is older than the parameter defining the maximum age * i allows.

An advantage of the method and system of the invention is that it avoids the use of limited camera resources in a situation where the desired image file may be slightly older than real time. However, at the same time, the image server can advantageously minimize the delay in delivering the desired image 113326 3. Preferably, the image request is transmitted to the camera only if the buffer memory does not find the desired image and sufficiently new image.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will now be described in more detail with reference to the preferred embodiments, with reference to the accompanying drawings, in which: Figure 1 is a block diagram of a typical image server system; Figure 2 is a block diagram showing an exemplary structure of an image server; and Figure 3 is a flow chart illustrating the steps of the method of the invention.

DETAILED DESCRIPTION OF THE INVENTION

Figure 1 is a block diagram illustrating a typical image server system in which the procedure of the invention can be applied. In Figure 1, two cameras 102, 104 are connected to the image server 100. The cameras may be in-frame still cameras or video cameras known per se, the image information of which may be stored in digital form. Thus, the camera may also be an analog camera, the image information of which is converted and stored in digital format on some other medium comprised by the image server. Further, the camera may be connected to the image server either via a wired or wireless connection and there may be: a separate communication network between the camera and the image server. From the user terminals 106, 108, 110: **, · sending, via network 112, image requests 100 to the image server 100. On the basis of this, the image server controls the cameras 102, 104. The network 112 may be any: a communication network known per se, such as a LAN LAN, a wide area network WAN or, for example, the Internet. Further, network 112 may be any wireless communication network, such as a wireless local area network (WLAN), a Bluetooth network, or a mobile communication system such as a GSM or UMTS network.

Cameras 102, 104 are arranged to capture images and their panorama: 30 angles, focus ratios and the like can be controlled by external commands transmitted by the image server. The control unit 114 controls the cameras 102, 104 in response to requests from users. Authentication Unit .::: 116 manages camera access and performs user authentication.

The transmission and reception unit 118 receives image requests sent by users via network 112 and transmits images corresponding to the image requests received by cameras 102, 104, respectively.

Similarly, a typical user terminal 110 also comprises a transmitting and receiving unit 120, which is arranged to send image requests to the image server 5 through network 112 and to receive images transmitted by the image server, respectively. The images transmitted by the image server are further transmitted from the receiving unit 120 to the display unit 122. Further, the user terminal 110 comprises input means 124 for determining a user image request, which image requests are forwarded to the transmission unit 120 for transmission over the network 112 to the image server 100.

In the following, the structure of the image server 100 will be described in more detail with reference to Figure 2. In the block diagram of Figure 2, the image server 100 comprises a processing unit CPU 200 which performs various image server control functions. The image server further comprises ROM 202 for storing various control programs executed by the processing unit 15. The process unit 200 uses RAM 204 as a working area when executing said control programs. The camera interface 206 receives an image signal from the camera 102. The control interface 208 controls the panoramic angle, the focus ratio, and other camera 102 parameters. Through the network interface 210, a distance 20 is provided between the users connected to the network 112 and the image server 100.

·; In accordance with a preferred embodiment of the invention, the image server 100 i · * ·: also includes a buffer memory 212 for images captured by cameras 102,104 • | ! ethene. The procedure for processing buffered images according to the invention will be explained in more detail later. The image server 100 may also comprise: a user interface means 214, such as a display and a keyboard, for providing various control commands to the image server, in particular the processing unit 200. The aforementioned units and components are interconnected by a bus 216. Referring to FIG. 1, the control unit 114, the recognition unit 116, and the transmit and receive unit 118 carry out operations which are in practice performed as a program stored in the ROM 202 executed by the processing unit t '': 200. allocated RAM 204.

The camera 102 further comprises an image signal of the imaging unit 218. v. for input to the camera interface 206. The camera 102 further comprises a control unit 35 for adjusting the control commands from the control interface 208, such as the frame angle of the input 113326 5, and making corresponding adjustments to the camera unit.

In known image server systems, there are a number of policies and protocols whereby image requests 5 made by users can be formatted as image requests understood by the image server. The image request from the user terminal 110 typically comprises the desired camera ID, user ID and possibly password, by which the authentication unit 116 authenticates the user and verifies the user's access to that camera. In addition, the Image Request comprises camera control commands, such as a panoramic angle, and an aspect ratio, based on which the camera is adjusted to take the desired image. Further, the image request can specify whether the desired image is desired once, periodically, or multiple successive images over a period of time, such as a video clip for a period of 5 seconds. The video sequence may also be generated internally on the server such that the server receives individual still images of the still image camera tracks at specified intervals and combines them into a separate video sequence which is transmitted to the user terminal. Thus, the image request may comprise a plurality of different parameters by which the acquisition of the desired image or images is controlled by the image server 100.

According to the invention, a new parameter, the maximum image age, is assigned to the ku-20 request transmitted from the user terminal 110, which defines how old the image can be sent to the user if other parameters of the image are

• I

: “Matches the parameters specified in the image request. Further, the image server 100:.:: Comprises a buffer memory in which images taken by the cameras are temporarily stored with a time stamp attached to the image file during recording:: i (i 25 which defines the time at which the image was taken. This is typically different: '· The time as the moment of recording. The buffer memory comprises for each of its parameters:';

• I>

Now, according to the invention, when the image server 100 receives an image; . , a request from a user terminal, checking the amount of data contained in the image request. ; 30 and compare them with the parameters of the images in the buffer memory. If there is an image file in the buffer memory whose parameters match the parameters of the image request f '·', the maximum image age specified in the image request is compared! parameter in the timestamp of that image file. If the timestamp indicates that the capture time is within the maximum allowed age, send-> * · ''. 35 directly from the image buffer memory to the requesting user terminal. Also, since the image request is not automatically transmitted to the camera, the limited resources of the camera are preferably not unnecessarily burdened. However, at the same time, the image server can advantageously minimize the delay in delivering the desired image.

The image request will only be transmitted to the camera if either of the above-mentioned conditions is not met; that is, if no image specified by the image request parameters is found in the buffer memory, or if the image specified by the image request parameters is found in the buffer memory, but its timestamp indicates that the image was taken older than the maximum age parameter. The image request is then forwarded to the camera, which processes the image requests in ascending order. 10 The captured image and the timestamp defining the time at which the image was captured are stored in a buffer memory, which typically operates on a FIFO (First-In-First-Out) basis. In this case, while the new image with certain parameters is stored in the buffer memory, the oldest image with the same parameters is deleted from the buffer memory. For example, the buffer memory may be implemented such that images according to certain parameters are stored in the buffer only one block at a time. This minimizes the need for buffer memory capacity. While the image server stores the captured image in the buffer memory, it also sends the image to the requesting user terminal.

This can advantageously reduce the image server loading load problems typically caused by the slow response of the shared resource, i.e. the camera, to the request made. If the image request frequency is high, the desired image will usually be found directly in the image buffer * *: no image request need be transmitted to the camera. Particularly, the procedure has an advantage • »: when using wireless cameras, because the wireless transmission path between the camera: [[['25 and the image server, and typically for wireless data transmission:' · this image file compression often causes image capture and transmission *. ' . of the image server.

According to a preferred embodiment of the invention, the parameter defining the maximum age; Vi is user definable. Alternatively, the maximum age of the image file may also be terminal-specific or image-specific; 'Per-default default value for a specific terminal or server'; Image requests for i always include the same value for the maximum age: ": parameter.

. '^ The image requests to be submitted are typically standard requests, i.e., image requests; '. The user terminals associated with the 35 brothers often request images with the same parameters and at certain time intervals. Thus, according to a preferred embodiment of the invention, if no image corresponding to the given conditions is found in the buffer memory, the image requests are set to the camera in multiple queues such that a different queue is formed for each different parameter combination. Then, when the camera 5 takes the first request in the image request queue and saves it in the buffer memory with a timestamp, it is advantageous to check the queue image requests before taking the next image, and if this last captured image matches the request 10, and the request may be removed from the camera queue.

Since image requests are typically standard requests, in a time when the server or cameras do not have queued image requests, in accordance with a preferred embodiment of the invention, the images most commonly requested by the cameras are captured and transferred to the image server buffer 15. The likelihood that the image file corresponding to the displayed image file is found directly in the buffer memory is further increased.

In the following, the method according to the invention will be described essentially with reference to the flow chart of Figure 3. The image server receives an image request (300) sent by a user terminal. Next, the image server checks the parameters (302) of said image request and compares said parameters with the para meters (304) of the image files contained in the buffer memory. This comparison step checks whether a buffer memory is found; an image file whose image definition parameters correspond to the parameters specified in said image request. If such an image file having parameters corresponding to the parameters of the displayed image request is found, the time stamp (306) stored next to said image file is next checked. If time-. . the stamp indicates that the image file in question is taken so that its age does not exceed the maximum age-specified parameter value specified in the image request, transmitting the image to the user terminal, which thus corresponds to the user terminal device. ; 30 image requests (308).

: 'If, in the first comparison step (304), it is found that: "The image file specified by the image request parameters is not found in the buffer memory, this Image request is forwarded to the camera (310). This also occurs if an image defined by the image request parameters is found. 35, but its timestamp indicates that the capture time is older than the maximum age allowed by the parameter: allows the user to proceed to the step of transmitting to the camera (310) an image request made by the camera. that is, a timestamp indicating the time at which the image was taken (312) is applied, and then returning to the step of transmitting the image defined by the image request to the user terminal in response to the image request (308) from the user terminal.

Referring to FIG. 2, the above operations may advantageously be performed as software stored in ROM 202 executed by the processing unit CPU 200 in the reserved state of the RAM 204. The software is configured to receive image requests through network interface 210 whose parameters are tracked by the software to check and compare the parameters with the image files in the buffer memory 212 and their timestamps. If the desired image is found in the buffer memory 212, the software is arranged to transmit that image via the network interface 210 to the requesting user terminal 15. Further, if the desired image is not found in the buffer memory or the timestamp indicates it is too old, the software is configured to modify the image request parameters so that they can be transmitted to the camera via the control interface 208. Similarly, the software is arranged to store an image file from the image signal received from the camera through the camera interface 206 and a timestamp 20 associated therewith to a buffer memory 212.

It will be obvious to a person skilled in the art that as technology advances, the basic idea of the invention can be implemented in many different ways. The invention and its embodiments are thus not limited to the examples described above, but may vary within the scope of the claims.

• I

> s · (. * »ä» f ·· »

Claims (11)

A method of controlling an image server (100), to which the image server at least one camera (102, 104) is operatively connected and which image server is arranged to transmit image files taken with said at least one camera in accordance with prior art. determined parameters, for at least one user terminal (106, 108, 110), the image server comprising a buffer memory (212), in which said image files, taken in accordance with predetermined parameters, are arranged to be stored, to which image files a a timestamp which determines the shooting moment is arranged to be attached, characterized in that the method comprises the following steps: from the user terminal (106, 108, 110) an image request (300) is sent to the image server, which image request comprises said predetermined parameters and a parameter which determines the allowed maximum age of the image file, said predetermined parameters in said image request 15 being compared with the corresponding pa frame parameters (302) for the image files contained in the buffer memory, in response to the buffer memory comprising an image file (304) corresponding to said predetermined parameters in said image request, the parameter determining the allowed maximum age of the image file in said image request is compared with the timestamp (306) of the image file contained in said buffer memory, and • in response to the timestamp of the image file contained in said buffer. \: fert memory indicates that the shooting moment is within the frame that determines, ···. 'the allowable maximum age, said image file contained in the buffer memory is sent to »·!' '. The user terminal (308) that made the request. IN.!: The method according to claim 1, characterized in that, in response to the buffer memory, the image memory does not include an image file (304) corresponding to said predetermined parameters in said image request or the timestamp of the image file contained in the buffer memory. If the gaze exceeds the maximum allowed age (306), the said image request is transmitted to the at least one camera (310). ,; Method according to Claim 1 or 2, characterized in that * in the buffer memory is stored for each separate image request defined v: by means of said predetermined parameters at least the last image file (312). 113326 4. A method according to claim 2 or 3, characterized by the reduced image request sent to said at least one camera being stored in several different queues, so that in the same queue the image request is made according to certain predetermined parameters. Method according to any one of claims 2-4, characterized in that the at least one camera transmitted, queued image request is checked after each image stored in the buffer memory with the camera; In response to the buffer memory comprising an image file corresponding to said predetermined parameters in any image request queue, whose timestamp indicates that the shooting instant is within the frame that determines the allowed maximum age, said image file contained in the buffer memory is sent to the user terminal. who made the image request; and said image request is removed from the camera queue. Method according to any of the preceding claims, characterized in that the image request is transmitted from the image server to said at least one camera and a signal comprising image information from said camera to the image server via a wireless connection. 7. Image server (100), to which at least one camera (102, 104) is functionally connected and arranged to transmit image files taken with f): said at least one camera according to prior art certain parameters, to at least one user terminal (106, 108, 110), and comprising a • «: ·· *. Buffer memory (212), in which said image files taken in accordance with predetermined parameters are arranged to be stored, to which image files a timestamp which determines the shooting moment is arranged to be attached, • In the characterized image server, is arranged to receive (300) an image request from the user terminal, which image comprises said predetermined parameters and a parameter ': which determines the maximum file age of the image file, ·: · ·· compare (302) said predetermined parameters in said ..... · image request with corresponding parameters for the image files contained in the buffer memory, in response to the buffer memory comprising an image file (304) corresponding to> said predetermined parameters in said image request, compare the 113326 (306) parameter which determines the allowed maximum age of the image file in said image request with time the image file stamp contained in said buffer memory, and in response to the timestamp of the image file contained in said buffer memory indicating that the shooting moment is within the frame that determines the allowed maximum age, transmitting (308) said image file contained in the buffer memory to the user terminal that made the request. The image server according to claim 7, characterized in that in response to the buffer memory not comprising an image file (304) corresponding to said predetermined parameters in said image request or the time file of the image file contained in the buffer memory indicates that the shooting moment exceeds the allowed maximum (306), the image server is arranged to transmit said image request (310) to said at least one camera. Image server according to claim 7 or 8, characterized in that the image server is arranged to store in the buffer memory for each separate image request defined by said predetermined parameters at least the last image file (312). Image server according to any of claims 7 to 9, characterized in that a wireless connection is arranged between the image server and said at least one camera. 11. Computer program for controlling an image server (100), which computer program comprises a programmatic code for storing image files taken in accordance with predetermined parameters and a timestamp which determines their deletion. photography moment in a buffer memory (212) which is part of the image server, the character of said computer program further comprises a programmatic code for receiving (300) an image request from a user terminal, which image request comprises said pre-determined; * 30 da parameters and a parameter that determines the allowed maximum of the image file, •: a programmatic code for comparing (302) the predetermined parameters in said image request with corresponding parameters for the image files contained in the buffer memory; a programmatic code for comparing (306) the parameter that determines the allowed maximum age of the image file in said bi Image request with the timestamp for the image file contained in said buffer memory in response to the buffer memory comprising an image file (304) corresponding to said predetermined parameters in said image request, and a programmatic code for transmitting (308) of the image file comprising in said buffer memory to the user terminal which made the request in response to the timestamp of the image file contained in said buffer memory indicating that the instant of photographing is within the frame (306) which determines the allowed maximum age. * · T »·» · · · · · · · · · · 1 · • «t • t • · *» 1 • · · * 1 • »» »» ·